Question

If the discriminant of the equation 2x2 – kx – 4 = 0 is 64, then find k.​

Answer 1

Answer- The above question is from the chapter 'Quadratic Equations'.

Let's know about quadratic equation first.

Quadratic equation- A polynomial whose highest power of variable is 2 is called a quadratic equation.

Examples:

1) x² + 2x + 2 = 2

2) 2x² + 4x + 1 = 0

Relationship between zeroes and coefficients of a quadratic equation:

Let ax² + bx + c = 0 be any quadratic equation.

Let α and β be its zeroes.

Sum of zeroes i.e α and β= -b/a

Product of zeroes i.e αβ= c/a

Discriminant (D) = b² - 4ac

Given question: If the discriminant of the equation 2x² - kx - 4 = 0 is 64, then find k.​

Solution: Given quadratic equation- 2x² - kx - 4 = 0

Here, a = 2, b = -k and c = -4

To find- Value of k

We know that, D = b² - 4ac

Substituting the values, we get,

64 = (-k)² - 4 × 2 × -4

k² = 64 - 32

k² = 32

k = ± √32

k = ± 4√2

∴ k = ± 4√2

Answer 2

Answer:

yeengdmgdynehgkeyjgjfjfurkfjdkgk